Metallurgical induction furnace



Aug. 2l, 1945- J. c. HARRIS, JR

ME'TALLURGICAL I'NDUcTLoN FURNAGE Filed July 18,` 1944 Car-bon BlokFic?? 2 d ba rl @N5 IIIUIHI? INVHVTOR. James C Harris, Ji:

Patented l21, 1945 ME'rALLUnGrcAL INDUCTION FUnNsoE .romeo conoonai-ris, Jr., Philadelphia, ro.A 4.application .my 1s. 1944, serial No.545,425

3 Claims.

'This invention relates, generally, to electric metallurgical furnaces,-and it has particular relation to furnaces of the horizontal open ringtype, as disclosed in my Patent No. 2,079,610, issued May l1, 1937.

An object of the invention is to improve th operating characteristics ofa furnace of this through tno bottom of the 'nog ohannn in the furnacebody I2. lt will be understood that the tap opening It can be located at'any other convement point.

The furnace construction herein described particularly well adapted tomelt and refine nonferrous metals, such as aluminum, manganese,

type, so that it is adapted to melt non-ferrous metals.

Another object of the invention is to increase the resistance of aportion of the secondary circuit over the balance thereof, formed by themetal being melted and rened.

A further object of the invention is to improve the vpower factor ofsuch a furnace and to increase its eiiiciency' in generating heat tolmelt and refine the metal.

Other objects of the invention will, in part, be

- obvious and, in part, appear hereinafter.

For a more complete understanding of the nature and scope of thisinvention, reference can be had to the following detailed description,

taken together withv the accompanying drawin which: Figure l is a topplan view' of a single phase furnace embodying the invention; and Figure2 is a detail sectional view taken along the line 2-2 of Figure' 1.

Referring now to Figures-1 and 2, it wm be noted that the referencecharacter Ill designates the primary circuitor winding of the furnacewhich, it will be understood, isA arranged to be connected to a suitablesource of alternating cur..

magnesium; copper, and alloys thereof. Such metals have low electricalresistanceand 'high electrical conductivity. Because of this, theresistance of the secondary circuit, lwhen formed only of such metals,is low and the rent flow is relatively high, being limited only by theeilective impedance of the transformer or furnace as a whole. As aresult, the power factor of the furnace is relatively low and it cannotoperate efficiently.

With a view to overcomingy the foregoing dlfilculty, there is provided ator in series circuit relation with the secondary c t formed by them'etal i4 in the form of a b ck 20 of carbonaceous material, suchi as amolded carbon or graphite block. I'he block 20 is shown as completelychoking the channel I3 in the charging hearth with its opposite sides incontact with the metal I4. It is preferably frictionally mounted ingrooves to prevent it from noating on the molten metal. However, it maybe held in plante` by any convenient means.

In order to start the furnace, a small `charge of molten metal can beladled into the channel Il, sufficient to complete the secondarycircuit,

rent, such as a 60 cycle source. 'The' primary circuit or winding i0surrounds the central leg of a three-legged core or transformer Hoflaminated magnetic material of the kind used in ordinary transformerconstruction.

A generally rectangularly shaped furnace .l2 of suitable refractorymaterial, extends through the windowsv of the "core Il, and has formedtherein a channel I! in which the metal I4, tobe meltedand renned, islocated. It

will be understood that the metal Il forms a part of the secondarycircuit of the transformer intowhich current is induced by the primarycircuit or winding l0 for the generation of heat to accomplish themelting and renning operation.

There is provided a charging chamber or hearth I5 which has an inclinedwall portion 'IG 4merging with the bottom wall of the ring chan--l nelI3. The purpose of this arrangement of the charging hearth l5 is fullyset forth in the aforesaid patent.

A plug l1 serves to close a tap opening il l pieces of the metal orpowdered metal are used with the resistor or block 20 forming a part.Alternatively, gas or oil jets (not shown) can be used initially to melta small charge. Moreover, the furnacev can -be made self-starting ifsmall to complete the secondary circuit. l

If the furnace is used principally for melting and refining aluminumftherefractoryforming` the furnace body I2 should have a high aluminum oxide(A1205.) content. r o

While the invention khas been disclosed in con- Junction with a singlephasefurnace, it can bev embodied in a .three phase furnace such asthat' disclosedin Patent No. 2,079,610. In suchaconstruction there wouldbe provided a high resistance, conducting 'block or resistor, individualto each phase.

Binlcevcertain further changes 'can be made in the foregoingconstruction. without departing from the spirit and scope of theinvention, it is intended that all matter shown in the accomslpanyingdrawing or described herein', shall be interpreted as illustrative 'andnot in a. limiting sense.

What is claimed is:

i. In an electric, induction furnace of the horil zontal open ring type,s. high resistance electrically conducting block choking the ringchannel sind forming a. portion of the secondary.

2. In an electric induction furnace of the horizontal, open ring typefor melting and refining metal. an electrical conducting member chokingAthe ring channel and having an electrical 'resist-

